The present invention relates to a gear drive apparatus with power branching for converting a rotational input into a predetermined rotational output.
Appended or add-on gear units having internal power branching in the form of a planetary arrangement or an axially freely adjustable gear with a herringbone tooth arrangement are known, whereby the gear unit typically includes an input shaft and an output shaft. Such add-on gear units, which are used, among other purposes, for driving generators in response to rotational inputs by rotors of wind power arrangements, are most often connected via a press fit coupling with the shaft of the rotor. In this conventional configuration, the hub of the press fit couplings is, most typically, a component of a planetary gear support and located inside the gear housing. The planetary gears of the encircling planetary gear carrier mesh with the inner gear teeth of a gear which is fixedly secured to the gear housing and these planetary gears mesh with, at the same time, a sun gear through which the power is combinatorily integrated. The levels of such planetary gear units can comprise three, four, five, or even, six, planetary gears. The power from the shaft of the sun gear in the primary level of such arrangements is converted either by an additional planetary gear level with a spur gear level which is driven by the output of this primary gear level or by two serially arranged spur gear levels, each of which is configured with a simple helical gear arrangement, and the power is then transferred to a generator.
The known gear drive arrangements are too complex for the higher level power output classes, as well as being too heavy and are subject, due to the high torque or torsional moments in combination with the relatively large dimensions of the arrangements, to large deformations and the non-uniform load distributions which result from such deformations. Such known gear drive arrangements include large assembly dimensions. Moreover, in the event of a repair of such a gear drive arrangement on the tower of a wind power arrangement, typically, no toothed components or bearings of the planetary gear arrangement can be exchanged. A disassembly of the complete gear drive arrangement or larger sub-assemblies of such a gear drive arrangement requiresxe2x80x94in particular, in connection with offshore arrangementsxe2x80x94relatively expensive crane capacities. A further disadvantage is that, with increasingly larger gear drive arrangements and 4 pole generators in the 60 hertz level, such gear drive arrangements are increasingly heavier and it is difficult with conventionally available shaft bearings to realize a sufficiently long bearing operational life for the high rates of rotation without exceeding the maximally allowable revolutions per minute stipulated by the bearing manufacturers.
The present invention provides a solution to the challenge of providing a gear drive apparatus which is characterized as a relatively compact and non-heavy assembly which is, moreover, simple to mount and assemble as well as to disassemble.
The gear drive apparatus of the present invention can be deployed as a gear or speed step-up drive as well as a gear or speed reduction drive. The gear drive apparatus has, for a speed step-up arrangement at a rapid speed, an input shaft and two output shafts. In connection with a configuration of the gear drive apparatus as a speed reduction arrangement to reduce the output rotational speed to a relatively slower speed, two motors drive a single rotational output shaft via two input shafts. The gear drive arrangement, which is preferably configured as an add-on arrangement, is advantageously deployed as a speed step-up arrangement in connection with the drive of wind power generators. In connection with a deployment of this type, the gear drive apparatus of the present invention provides the most significant advantages. In connection with a speed reduction arrangement, the gear drive apparatus of the present invention can be deployed, for example, to drive the operation of rod mills or cutting heads of excavators or shovels.
Due to the particular bearing support and location of the individual shafts to one another, the gear drive apparatus of the present invention provides a symmetrical drive arrangement with a center of mass located in the principal axis. Up to two pinion shafts having gears can be deployed for meshing engagement with the large gear and all of the gears and bearings of such an arrangement can be disposed in a gear housing with three parting lines. In connection with the use of the gear drive apparatus of the present invention in a wind power arrangement, a virtually complete disassembly or a virtually complete exchange of parts on the tower of the wind power arrangement is possible with the use of only limited crane capacity.
Due to the power distribution and gear arrangements of the gear drive apparatus of the present invention, the power transmission capabilities of the teeth of the large gear are optimally used or exploited and, thus, the torque conversion is optimally exploited.
Via the arrangement of the anti-friction bearings of the eight pinion shafts operably connected with the large gear in two parallel and torsionally mutually stiffened gear housing walls, which are, at the same time, configured as torque or torsional moment fulcrums, there is provided a very torsionally stiff gear drive apparatus, whereby the disadvantageous deformations of a planetary gear drive apparatus are not present.
The present invention provides an optimal access to all of the bearing locations and the gear teeth meshing locations for the purpose of providing lubrication thereto and for conducting a temperature monitoring of the bearing locations.
Due to the reproducibility of many of the internal components of the gear drive apparatus of the present invention, a cost favorable production of the gear drive apparatus of the present invention is possible with proportionally reduced rigging costs and a cost favorable replacement part outlook.
The position of the rapidly rotating output shaft is selected such that the two generators of the wind power arrangement can be optimally located relative to one another. The distance between the generators provides sufficient access.
The gear drive apparatus of the present invention makes possible, in contrast to a conventional planetary gear drive apparatus, the disposition of a press fit disc or cinch collar for transferring the torque of the rotor shaft in the hollow access or shaft of the gear drive apparatus at both the output side and the input side of the gear drive apparatus. With the gear drive arrangement of the press fit disc or cinch collar on the rotational output sidexe2x80x94which is not possible in connection with a planetary gear drive apparatusxe2x80x94it is possible to achieve the smallest possible total assembled length.
In connection with the operation of the gear drive apparatus of the present invention, it is possible to deploy the gear drive apparatus as an add-on gear drive apparatus for a rotor shaft separately supported at two locations or, at the same time, as the second bearing support of a rotor shaft as has often typically been configured. The gear drive apparatus of the present invention can also be configured as an add-on gear drive apparatus without a bearing support function between the bearing supports of the rotor. This has the advantage that a large distance between the bearing supports of the rotor shaft can be achieved.
A bore for the passage therethrough of a control conduit to control a change of pitch of the rotor of the wind power arrangement can be directly configured in the rotor shaft so that the need to provide a special purpose conduit, as has heretofore been required, for achieving a change of pitch of the adjustable pitch rotor, can be dispensed with.
In the event of a fall out or stoppage of a generator, the gear drive apparatus of the present invention is still fully capable of functioning because the power integrations of the individual gear lines occur independently of one another.
Due to the power branching and/or the power integration by means of two axially freely supported high speed output shafts having herringbone gear teeth, the shaft dimensions are smaller than those of a mono-generator drive. Due to the absence of axial bearing supports for the shafts, it is also possible, in connection with very high excess or overspeed revolutions per minute of these shafts, to deploy conventionally available shaft bearing supports which bring with them sufficient bearing operational life.